We hypothesized that the addition of mitral valve replacement or repair (MVR) to implantation of continuous-flow left ventricular assist device (cf-LVAD) may further decrease pulmonary vascular resistance (PVR) over Heartmate II (HMII) implantation alone. Patients undergoing MVR with concomitant HMII implantation were compared with those undergoing HMII implantation alone. Of the 57 patients undergoing cf-LVAD implantation, 21 (36.8%) underwent concomitant MVR and 36 (63.2%) underwent cf-LVAD implantation alone. Patients receiving MVR had greater decrement in PVR (59.4% vs. 35.2%, p = 0.01). Decrease in end-diastolic diameter was greater for patients receiving MVR but did not reach statistical significance (18.2 vs. 13.5 mm, p = 0.33). Duration of mechanical ventilation (121.6 vs. 181.4 hours, p = 0.45) and inotropic support (162.4 vs. 153.2 hours, p = 0.86), change in creatinine (0.19 vs. -0.26 mg/dl, p = 0.34), increase in bilirubin (2.54 vs. 1.55 mg/dl, p = 0.63), intensive care unit stay (168.0 vs. 231.5 hours, p = 0.38), and overall length of stay (32.0 vs. 42.5 days, p = 0.75) were similar. There was no difference in survival at 3 months (89.7% vs. 83.3%) and 1 year (83.7 vs. 67.3%, p = 0.34). Addition of MVR may result in greater decrement of PVR than HMII implantation alone. This may permit certain patients thought to be ineligible for transplantation to become candidates.